A radius looks simple on screen, but turning it into a trustworthy profile takes several deliberate steps. Here is what happens between dropping a pin and reading the numbers.
From pin to polygon
The pin is converted to a projected circle. Because the earth is not flat, we project to a local coordinate system first so the radius stays a true distance rather than stretching with latitude.
Selecting geographies
We intersect the circle with the underlying collection geographies, then weight each one by the share of its area that falls inside the boundary.
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Image with heatmap panel open
Building the profile
- Aggregate each demographic attribute across selected geographies.
- Normalise for the partial overlap at the boundary.
- Attach the Representation Score so you know how much to trust the result.
The result is a profile that behaves sensibly as you drag, resize, or duplicate a radius across a region.